In today's technological world, there is an increasing need for membrane switch assemblies that can be mounted on hemispherical surfaces such as cathode ray tubes (CRT's). An ever increasing amount of software is becoming available that requires the user to answer questions by pressing appropriate areas of a CRT equipped with a membrane switch assembly.
These assemblies are generally made from two layers of essentially transparent film, the internal surfaces of each layer having conductors deposited thereon, separated by a third layer of film containing openings for switch sites. The conductors on the layers cross and are normally spaced from each other at the switch sites.
When such a device is operated, it is highly desirable that the assembly be essentially optically clear to the operator. For this reason, assemblies having wide conductors are generally unacceptable. The wide conductive traces are visible to the naked eye. Assemblies of the type having narrow conductors, particularly hairline conductors are generally more acceptable.
Use of hairline conductors can cause problems in forming the layer of film to the desired hemispherical radius in that the hairline conductors break during the forming process, thus rendering the switch inoperable. Hemispherically forming the circuit layers according to the method as disclosed herein, solves the abovementioned problem. An apparatus for the performing the method is also disclosed herein.